U.S. patent application number 13/321289 was filed with the patent office on 2012-06-28 for ionizer and electrostatic charge eliminating system.
Invention is credited to Masahiko Ito, Yoshiaki Sato.
Application Number | 20120162848 13/321289 |
Document ID | / |
Family ID | 43223333 |
Filed Date | 2012-06-28 |
United States Patent
Application |
20120162848 |
Kind Code |
A1 |
Ito; Masahiko ; et
al. |
June 28, 2012 |
IONIZER AND ELECTROSTATIC CHARGE ELIMINATING SYSTEM
Abstract
In an embodiment of the present invention, an ionizer and an
electrostatic charge eliminating system are provided in which
optional functions can be operated without increasing a current
consumption when a timing of operating the optional functions is
shifted in a case where a plurality of ionizers having optional
functions such as a cleaning function are simultaneously used or an
ionizer having a plurality of optional functions is used. According
to an embodiment of the present invention, an ionizer includes:
control portion 7; cleaning portion 10 operated when a command is
given from control portion 7; first timer 5 for measuring a waiting
time from a time at which a power source is turned on to a time at
which cleaning portion 10 executes an operation at a first time;
and second timer 6 for measuring a cycle time so that cleaning
portion 10 can repeatedly execute the operation at a second time or
later by a predetermined cycle time.
Inventors: |
Ito; Masahiko;
(Sagamihara-City, JP) ; Sato; Yoshiaki;
(Fujisawa-Shi, JP) |
Family ID: |
43223333 |
Appl. No.: |
13/321289 |
Filed: |
May 26, 2010 |
PCT Filed: |
May 26, 2010 |
PCT NO: |
PCT/US10/36115 |
371 Date: |
November 18, 2011 |
Current U.S.
Class: |
361/213 |
Current CPC
Class: |
H01T 23/00 20130101 |
Class at
Publication: |
361/213 |
International
Class: |
H05F 3/06 20060101
H05F003/06 |
Foreign Application Data
Date |
Code |
Application Number |
May 29, 2009 |
JP |
2009-131105 |
Claims
1. An ionizer for eliminating an electrostatic charge from an
object by neutralizing said electrostatic charge when air ions are
blown to said object which is electrically charged with static
electricity and from which said electrostatic charge is to be
eliminated, said ionizer comprising: a control portion; a
functional portion operated when a command is given from said
control portion thereto; a first timer for measuring a waiting time
from a time at which an electric power source is turned on to a
time at which said functional portion executes an operation at a
first time; and a second timer for measuring a cycle time so that
said functional portion can repeatedly execute said operation at a
second time or later by a predetermined cycle time.
2. The ionizer according to claim 1, wherein said functional
portion is a cleaning portion for cleaning a discharge electrode
which generates a corona discharge with an opposed electrode.
3. The ionizer according to claim 1, wherein said first timer
includes a random circuit for setting said waiting time at said
first timer.
4. The ionizer according to claim 1, further comprising: a control
unit having said control portion, said first timer and said second
timer; and a plurality of electrostatic charge eliminating units
respectively having said functional portions, wherein said control
portion makes said first timer measure said waiting time and also
makes said second timer measure said cycle time, and controls the
plurality of electrostatic charge eliminating unit so that said
functional portions of said electrostatic charge eliminating units
can be operated in order.
5. The ionizer according to claim 1, further comprising: a signal
detecting portion for detecting a voltage level of a common
operation signal line electrically connected to a plurality of
ionizers; and a signal outputting portion for outputting an
operation signal to said common operation signal line so as to
decrease a voltage level of said common operation signal line to a
value lower than a predetermined voltage level when said functional
portion is operated, wherein said control portion judges a timing
to operate said functional portion according to said voltage level
detected by said signal detecting portion.
6. An electrostatic charge eliminating system having a plurality of
ionizers for eliminating an electrostatic charge from an object by
neutralizing said electrostatic charge when air ions are blown to
said object which is electrically charged with static electricity
and from which said electrostatic charge is to be eliminated,
wherein the plurality of ionizers are supplied with electric power
from a common electric power source, each ionizer including: a
control portion; a functional portion operated when a command is
given from the control portion thereto; a first timer for measuring
a waiting time from a time at which an electric power source is
turned on to a time at which said functional portion executes an
operation at a first time; and a second timer for measuring a cycle
time so that said functional portion can repeatedly execute said
operation at a second time or later by a predetermined cycle time,
wherein each ionizer operates said functional portion while a
timing of operating said functional portion is being shifted.
Description
TECHNICAL FIELD
[0001] The present invention relates to an ionizer and an
electrostatic charge eliminating system for eliminating an
electrostatic charge from an object by neutralizing the
electrostatic charge when air ions are blown to the object which is
electrically charged with static electricity and from which the
electrostatic charge is to be eliminated.
BACKGROUND
[0002] An example of the ionizer for eliminating an electrostatic
charge from an object such as an IC chip or an electronic part
having an insulating property is an air blasting type ion
generating device described in Official gazette of
JP-A-2004-234972. In the paragraph No. 0021 of Official gazette of
JP-A-2004-234972, a means for generating air ions is described as
follows. "Ion generating means 9 includes: annular opposed
electrode 14 attached onto an outer circumference of air ion guide
cylinder 12 made of insulating material connected to a front
portion of shroud 11; and 8 discharge needles 15 radially arranged
at regular intervals in a circumferential direction of the opposed
electrode 14 in air ion guide cylinder 13. These discharge needles
15 are implanted in rod-shaped electrode holder 16 made of
insulating material arranged in a central portion of air ion guide
cylinder 13. Output cable 17a of high voltage AC power source 17
arranged in an inner bottom portion of case 4 is connected to
discharge needles 15 through conductor 18 embedded in electrode
holder 16. Return cable 17b of high voltage power source 17 is
connected to opposed electrode 14. A corona discharge is generated
between discharge needles 15 and opposed electrode 14 so as to
generate positive and negative air ions."
[0003] In the paragraphs Nos. 0022 to 0024, a cleaning means for
removing dust from tips of the discharge needles is described as
follows. "Cleaning means 10 includes: rod-shaped rotary member 20
rotated by a wind force having fin portion 19 with which an air
current sent from air blasting means 8 collides; and brush member
21 attached to rotary member 20 through fin portion 19 (0022). A
center in a longitudinal direction of rotary member 20 is supported
by supporting portion 22 arranged in the front of electrode holder
16. Rotary member 20 can be freely rotated about a concentric axis
with an annular center of opposed electrode 14 (0023). Brush member
21 is made of plastics such as nylon resin or acrylic resin. Brush
member 21 is attached at a position in a radial direction
corresponding to a distance from an annular center of opposed
electrode 14 to a tip of each discharge needle 15 through brush
attaching member 23. When rotary member 20 is rotated, brush member
21 comes into contact with the tips of discharge needles 15
(0024)."
SUMMARY OF THE INVENTION
[0004] In general, an operation current to operate an ionizer
having an electric fan is approximately 1 A. However, when a
cleaning function for cleaning a discharge electrode (a discharge
needle) is added, a current to drive a brush for cleaning is added
to the operation current of the ionizer. Therefore, a total current
is multiplied by several times. In a case where a plurality of
ionizers are used for a manufacturing line, in which electronic
parts are manufactured, such as a semiconductor manufacturing line,
electric power sources of the plurality of ionizers are totally
turned on and off by a main power source switch. Accordingly, a
total electric current consumption for simultaneously operating all
the ionizers is further increased. For example, when a plurality of
ionizers are used for an IC handler (a semiconductor chip conveying
device), it is necessary to sufficiently increase a current
capacity of the IC handler so that the operation of the device can
not be affected even when all the ionizers consume the respective
maximum current consumption.
[0005] In an embodiment of the present invention, an ionizer and an
electrostatic charge eliminating system are provided in which
optional functions can be operated without increasing a current
consumption when timing of operating the optional functions is
shifted in the case where a plurality of ionizers having optional
functions such as a cleaning function are simultaneously used or an
ionizer having a plurality of optional functions is used.
[0006] In one embodiment, the present invention provides an ionizer
for eliminating an electrostatic charge from an object by
neutralizing the electrostatic charge when air ions are blown to
the object which is electrically charged with static electricity
and from which the electrostatic charge is to be eliminated,
comprising: a control portion; a functional portion operated when a
command is given from the control portion to it; a first timer for
measuring a waiting time from a time at which an electric power
source is turned on to a time at which the functional portion
executes an operation at a first time; and a second timer for
measuring a cycle time so that the functional portion can
repeatedly execute the operation at a second time or later by a
predetermined cycle time.
[0007] In another embodiment, the present invention provides an
electrostatic charge eliminating system having a plurality of
ionizers for eliminating an electrostatic charge from an object by
neutralizing the electrostatic charge when air ions are blown to
the object which is electrically charged with static electricity
and from which the electrostatic charge is to be eliminated,
wherein the plurality of ionizers are supplied with electric power
from a common electric power source, each ionizer including: a
control portion; a functional portion operated when a command is
given from the control portion to it; a first timer for measuring a
waiting time from a time at which an electric power source is
turned on to a time at which the functional portion executes an
operation a first time; and a second timer for measuring a cycle
time so that the functional portion can repeatedly execute the
operation at a second time or later by a predetermined cycle time,
wherein each ionizer operates the functional portion while the
timing of operating the functional portion is being shifted.
[0008] According to the ionizer and the electrostatic charge
eliminating system of the present invention, when the timing of
operating the optional function is shifted, it is possible to
operate the optional function without increasing the current
consumption. Due to the foregoing, it is possible to simultaneously
use a plurality of ionizers having an optional function such as a
cleaning function. Further, it is possible to use an electrostatic
charge eliminating device having a plurality of optional
functions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a block diagram of an ionizer (an electrostatic
charge eliminating device) and an electrostatic charge eliminating
system of the first embodiment of the present invention.
[0010] FIG. 2 is a detailed block diagram of the ionizer shown in
FIG. 1.
[0011] FIG. 3 is a flow chart showing a cleaning operation of each
ionizer shown in FIG. 2.
[0012] FIG. 4 is a time chart at the time of a cleaning operation
executed by each ionizer.
[0013] FIG. 5 is a time chart at the time of a cleaning operation
executed by a plurality of ionizers at the same timing.
[0014] FIG. 6 is a time chart at the time of a cleaning operation
executed by a plurality of ionizers when the timing is shifted.
[0015] FIG. 7 is a block diagram of an ionizer and an electrostatic
charge eliminating system of the second embodiment of the present
invention.
[0016] FIG. 8 is a block diagram of each ionizer of the
electrostatic charge eliminating system shown in FIG. 7.
[0017] FIG. 9 is a circuit diagram of a plurality of ionizers of
the electrostatic charge eliminating system shown in FIG. 7.
[0018] FIG. 10 is a flow chart at the time of a cleaning operation
executed by each ionizer shown in FIG. 7.
[0019] FIG. 11 is a time chart at the time of a cleaning operation
executed by a plurality of ionizers shown in FIG. 7 when the third
timer is used while the timing is being shifted.
[0020] FIG. 12 is a time chart at the time of a cleaning operation
executed by a plurality of ionizers shown in FIG. 7 when the third
timer is not used while the timing is being shifted.
[0021] FIG. 13 is a block diagram of the ionizer of the third
embodiment of the present invention.
[0022] FIG. 14 is a detailed block diagram of the control unit of
the ionizer shown in FIG. 13.
[0023] FIG. 15 is a detailed block diagram of the electrostatic
charge eliminating unit of the ionizer shown in FIG. 13.
[0024] FIG. 16 is a flow chart at the time of a cleaning operation
executed by the ionizer shown in FIG. 13.
[0025] FIG. 17 is a block diagram of the ionizer of the fourth
embodiment of the present invention.
DETAILED DESCRIPTION
[0026] According to an embodiment of the present invention, an
ionizer (an electrostatic charge eliminating device) includes: a
control portion; at least one functional portion operated when a
command is given from the control portion to the functional
portion; a first timer for measuring a waiting time from a time at
which a power source is turned on to a time at which the functional
portion executes an operation at a first time; and a second timer
for measuring a cycle time so that the functional portion can
repeatedly execute the operation at a second time or later by a
predetermined cycle time. According to an embodiment of the present
invention, an electrostatic charge eliminating system includes a
plurality of ionizers that receive electric power from a common
electric power source. A functional portion of each ionizer has
optional functions such as a cleaning function and an air blasting
function operated when electric power is supplied from an electric
power source.
[0027] Referring to the drawings, an embodiment of the ionizer and
the electrostatic charge eliminating system of the present
invention will be explained below. FIG. 1 shows an ionizer and an
electrostatic charge eliminating system of the first embodiment of
the present invention. As shown in the drawing, although
electrostatic charge eliminating system 1 of the present embodiment
is not restricted by this embodiment, for example, electrostatic
charge eliminating system 1 of the present embodiment can be
applied to an IC handler of a semiconductor manufacturing system in
a clean room. Electrostatic charge eliminating system 1 includes a
plurality of ionizers 3a to 3d. Ionizers 3a-3d are connected to
electric power source 2 (for example, DC electric power source) in
parallel. Further, electric power source 2 is electrically
connected to an IC handler and various devices so that electric
power can be supplied. An allowable current of electric power
source 2 is decided at a predetermined ampere. Therefore, in a case
where an electric current, the intensity of which exceeds the
allowable current, is consumed, a breaker is operated. It is
typical that ionizers 3a to 3d of the electrostatic charge
eliminating system are connected to the electric power source of
the IC handler and others. However, ionizers 3a to 3d of the
electrostatic charge eliminating system may be connected to an
electric power source provided differently.
[0028] The number of ionizers 3a-3d is not limited to four but it
is possible to use ionizers, the number of which is two or more.
However, the number of the ionizers to be used is restricted by the
allowable current of electric power source 2. Ionizers 3a to 3d
used for the present embodiment have a cleaning function as an
optional function. Each ionizer used for the present embodiment has
second timer 6 for measuring a cycle time, at which a discharge
electrode to generate corona discharge together with an opposed
electrode (not shown) is cleaned, as a timer for measuring the
cycle time to periodically execute a cleaning function. Four
ionizers 3a to 3d are electrically connected to a main switch of IC
handler not shown. Therefore, the electric power source can be
simultaneously turned on and off by the main switch.
[0029] In general, the ionizer includes: a discharge electrode
arranged being opposed to the opposed electrode; an ion generating
portion for generating corona discharge between the opposed
electrode and the discharge electrode; and an air blasting portion
(a blower) for blowing the generated ions to an object from which
an electrostatic charge is to be eliminated. In the ionizer, when
ionized air is blown to the object from which an electric charge is
to be eliminated, the electrostatic charge can be eliminated from
the object.
[0030] An arrangement of the discharge electrodes can be
arbitrarily determined. It is typical that the discharge electrodes
are radially arranged in a direction perpendicular to the air
flowing direction. The number of the electrodes is determined
according to an electrostatic capacity and is not particularly
restricted. However, for example, the electrode, the number of
which is four, can be arranged at regular intervals. The discharge
electrode is made of, for example, tungsten alloy. Concerning its
dimensions, for example, the diameter is 1.5 mm and the length is
20 mm. Voltage applied to the discharge electrode is approximately
+, -5000v in a case of a DC type ionizer.
[0031] The air blasting portion is a device for generating a wind
force capable of blowing a blast of ionized air to an object from
which an electrostatic charge is to be eliminated. The air blasting
portion may be of the structure in which a fan is rotated by a
motor. Alternatively, the air blasting portion may be of the
structure in which a tube of compressed air is connected to the
ionizer and a blast of air is sent by the pressure of compressed
air.
[0032] As shown in FIG. 2, the ionizer of the present embodiment
includes: conventional ion generating portion 8; and air blasting
portion 9. Further, the ionizer of the present embodiment includes:
cleaning portion (an optional function) 10 for periodically
cleaning a tip portion of the discharge electrode so as to remove
dirt attached to the tip portion of the discharge electrode; first
timer 5 for measuring waiting time t.sub.1 from a time at which an
electric power source is turned on to a time at which cleaning
portion 10 executes an operation at the first time; waiting time
setting portion 11 for setting a waiting time at first timer 5;
second timer 6 for measuring cycle time t.sub.2 so that cleaning
portion 10 can be made to repeatedly execute the operation at the
second time or later by the predetermined cycle time; and control
portion 7 for giving a command to operate cleaning portion 10.
Cleaning portion 10 includes: a movable portion (not shown)
operated by a power source such as a solenoid or a motor; and a
brush (not shown) for removing dirt from the tip of the discharge
electrode when the brush is moved together with the movable
portion. Cleaning is carried out in such a manner that the brush is
reciprocated with being contacted with the tip of the discharge
electrode, for example, for several seconds to several tens
seconds. When the discharge electrode is cleaned, the ionizer
consumes an electric current, the intensity of which is several
times as much as the electric current consumed at the time of
generating ions. The waiting time, from a time at which the
electric power source 2 is turned on to a time at which the
operation of the cleaning portion 10 is started, is set at first
timer 5. A random circuit for automatically generating random
numbers can be applied to waiting time setting portion 11. However,
it is possible to set the waiting time in such a manner that an
operator manually turns a dial provided in the timer. In the same
manner, waiting time setting portion 11 can set cycle time t.sub.2
at second timer 6. In this connection, individual ionizers 3a to 3d
are not restricted by the form of the present embodiment but it is
possible to provide an optional function such as a wind direction
changing means for changing an air blasting direction.
[0033] FIG. 3 is a flow chart of cleaning individual ionizers 3a to
3d. When the electric power source of the ionizer is turned on in
step S1, the discharge electrode starts discharging and the ionizer
starts blowing a blast of ionized air. At the same time, first
timer 5 measures predetermined waiting time t.sub.1 (step S2).
After waiting time t.sub.1 has passed, cleaning portion 10 starts
an operation and the discharge electrode is cleaned (step S3).
Simultaneously when step S3 is started, second timer 6 starts
measuring the time. After predetermined cycle time t.sub.2 has
passed (step S4), cleaning portion 10 starts the operation again
and cleans the discharge electrode. After that, predetermined cycle
time t.sub.2 has passed, the discharge electrode is repeatedly
cleaned. In this connection, cycle time t.sub.2 may be constant.
Alternatively, cycle time t.sub.2 may be changed by a predetermined
pattern or at random so that the cleaning interval can be
changed.
[0034] FIG. 4 is a time chart at the time of a cleaning operation
carried out by one set of ionizer 3a to 3d. First timer 5 measures
waiting time t.sub.1 from a time at which electric power source 2
is turned on to a time at which a cleaning operation is started.
When waiting time t.sub.1 has passed, second timer 6 starts
measuring cycle time t.sub.2 that is arbitrarily decided and
cleaning is executed again. In the present embodiment, cycle time
t.sub.2 can be set, for example, at one hour. In each ionizer 3a to
3d of the present embodiment, the current consumption at the time
of generating ions is 1 A and the current consumption at the time
of cleaning is 2 A.
[0035] FIG. 5 is a time chart at the time of a cleaning operation
carried out by four sets of ionizers 3a to 3d at the same timing.
FIG. 5 shows a comparative example. As shown in the time chart,
when four sets of ionizers 3a to 3d are simultaneously operated,
the current consumption at the time of generating ions is 4 A.
Therefore, the total current consumption at the time of the
cleaning operation is 8 A. In order to operate each ionizer 3a to
3d at this timing, it is necessary to use electric power source 2,
the allowable current is not less than 8 A.
[0036] FIG. 6 is a time chart at the time of a cleaning operation
in which ionizers 3a-3d are operated at the shifted timing. As
shown in the time chart, waiting time t.sub.1a to t.sub.1d of first
timer 5 is set to be longer by 10 minutes from 10 minutes to 40
minutes so that the respective cleaning start timing can be shifted
at an interval of 10 minutes. Therefore, the cleaning operation of
the discharge electrode is not simultaneously executed.
Accordingly, the total current consumption at the time of the
cleaning operation can be suppressed at 5 A.
[0037] As described above, according to ionizers 3a to 3d and
electrostatic charge eliminating system 1 of the present
embodiment, the timing at which first timer 5 is operated is
shifted with respect to individual ionizers 3a to 3d. Accordingly,
the current consumption can be prevented from increasing.
[0038] Next, the ionizer and the electrostatic charge eliminating
system of second embodiment will be explained below. As shown in
FIG. 7, the electrostatic charge eliminating system of the present
embodiment includes: electric power source 2; and ionizers 23a to
23d. As shown in FIG. 8, each ionizer 23a to 23d includes: second
timer 6; first timer 5 for setting waiting time t.sub.1 by random
circuit 11; and third timer 28 for measuring waiting time t.sub.3
to a time at which a voltage level of common signal line 24 is
detected when other ionizer 23a to 23d is executing the cleaning
operation. Each ionizer 23a to 23d of the present embodiment
includes: signal detecting portion 25 connected to common signal
operation line 24 and detecting a voltage level of common operation
signal line 24; and signal output portion 26 for outputting an
operation signal to common operation signal line 24 so that a
voltage level of common operation signal line 24 can be
decreased.
[0039] FIG. 9 is a circuit diagram of a plurality of ionizers 23a
to 23d connected to common signal operation line 24. Signal
detecting portion 25 of each ionizer 23a to 23d detects whether the
voltage level of common operation signal line 24 is in high or low.
At the same time, signal detecting portion 25 of each ionizer 23a
to 23d judges that other ionizer 23a to 23d is executing the
cleaning operation when the detected voltage level is low. Signal
detecting portion 25 of each ionizer 23a to 23d judges that no
ionizers 23a-23d are not executing the cleaning operation when the
detected voltage level is high. When each ionizer 23a to 23d is
executing the cleaning operation, signal output portion 26 outputs
an operation signal, which is a minute electric current, to common
operation signal line 24 through transistor 27. Transistor 27 is of
the type NPN. When an operation signal (an electric current) is
sent from signal output portion 26 to the base, a resistance value
between the emitter and the collector is greatly lowered and the
voltage level of common operation signal line 24 becomes low. When
each ionizer 23a to 23d is not executing the cleaning operation,
signal output portion 26 does not output an operation signal. As a
result, the collector and the emitter are set in an open state from
each other. Accordingly, the voltage of DC power source V is
applied to the common operation signal line as it is. Therefore,
the voltage level becomes high.
[0040] FIG. 10 is a flow chart at the time of a cleaning operation
of each ionizer 23a to 23d. First timer 5 measures waiting time
t.sub.1 from a time at which the electric power source of ionizer
23a to 23d is turned on to a time at which the first time cleaning
operation is started. Second timer 6 measures cycle time t.sub.2 of
a predetermined cleaning interval. The third timer measures waiting
time t.sub.3 at which the start of the cleaning operation is
delayed when other ionizer 23a to 23d is executing the cleaning
operation. That is, in a case where the timing of cleaning is
overlapped with that of other ionizer 23a to 23d, the waiting time
for starting the cleaning operation is prolonged so as to shift the
timing.
[0041] Specifically, for example, in a case where cycle time
t.sub.2 of cleaning is set at one hour, it is set so that waiting
time t.sub.1 of first timer 5 can be set at random in range from 0
second to 50 minutes (subtracted 10 minutes from the cycle time) by
random circuit 11 in step SS2. After this time has passed, when the
voltage given to common operation signal line 24 is detected in
step SS3, it is checked whether or not other ionizer 23a to 23d is
executing the cleaning operation by using common electric power
source 2. In a case where other ionizer 23a to 23d is executing the
cleaning operation (Refer to FIG. 11.), the program proceeds to
step SS4 and the cleaning operation time is set at 10 seconds.
Then, waiting time t.sub.3 of the third timer is set at the time
longer than 10 seconds, for example, waiting time t.sub.3 of the
third timer is set at 20 seconds and it is checked again whether or
not other ionizer 23a to 23d is executing the cleaning operation by
using common operation signal line 24. In a case where no ionizer
23a to 23d is executing the cleaning operation (Refer to FIG. 12.),
the program proceeds to step SS5 and signal output portion 26
outputs an operation signal and makes a voltage level of common
operation signal line 24 to be low. Due to the foregoing, the
ionizer is made to be unable to execute the cleaning operation at
the same timing as that of other ionizer 23a to 23d. When the
cleaning operation is finished in step SS6, the voltage level of
common operation signal line 24 is returned to high in step SS7.
After the program has waited for predetermined cycle time t.sub.2
(step SS8) from step SS6, the program returns to step SS3 and the
cleaning operation is repeatedly executed. In this connection, it
is possible that the program is not returned to SS3 but returned to
SS6 at the second time and after that and the cleaning operation is
repeatedly executed. Waiting time t.sub.3 of the third timer can be
also set by the random circuit.
[0042] In the embodiment described above, even when waiting time
t.sub.1 of first timer 5 is not previously set so that a plurality
of ionizers 23a to 23d can not be overlapped with each other, it is
possible to prevent the plurality of ionizers 23a to 23d from
executing the cleaning operation at the same timing.
[0043] A variation of the present embodiment is described as
follows. In the ionizer, instead of watching the voltage of common
operation signal line 24 by using the third timer at predetermined
intervals, the voltage of common operation signal line 24 may be
detected at all times. In this variation, when the common operation
signal level is low in step SS3 in FIG. 10, the ionizer
continuously detects the common operation signal level. Then, when
it is detected that the common operation signal level is high, the
program can be transferred to step SS5. In other words, waiting
time t.sub.3 of step SS4 may be substantially 0 second. In this
case, the ionizer may not be provided with the third timer.
[0044] Next, the ionizer and the electrostatic charge eliminating
system of the third embodiment of the present invention will be
explained below. As shown in FIG. 13, the electrostatic charge
eliminating system of the present embodiment includes: electric
power source 2; and ionizer 31. Ionizer 31 includes: control unit
32; and a plurality of electrostatic charge eliminating units 33a
to 33d connected to control unit 32. Each electrostatic charge
eliminating unit 33a to 33d is connected to common electric power
source 2. As shown in FIG. 14, control unit 32 includes: control
portion 34; first timer 5; second timer 6; and communicating
portion 36 for sending and receiving signals from communicating
portions 36 of electrostatic charge eliminating units 33a to
33d.
[0045] As shown in FIG. 15 in which electrostatic charge
eliminating unit 33a is shown as a representation, each
electrostatic charge eliminating unit 33a to 33d includes: ion
generating portion 8; air blasting portion 9; cleaning portion 10;
and communicating portion 36 for sending and receiving signals from
communicating portion 35 of control unit 32. Communicating portion
36 sends a result of detecting the operation of cleaning portion 10
to control unit 32 and receives a command for starting the cleaning
operation from control unit 32. Control unit 32 gives a command of
starting the cleaning operation to each electrostatic charge
eliminating unit 33a to 33d according to delay time t.sub.1 and
cycle time t.sub.2 measured by first timer 5 and second timer 6.
The same communicating portion as communicating portion 35 of
control unit 32 can be used for communicating portion 36.
[0046] FIG. 16 is a flow chart for explaining an operation of the
electrostatic charge eliminating system of the present embodiment.
When a switch of ionizer 31 has been turned on (step SSS1) and
predetermined waiting time t.sub.1 has passed (step SSS2), control
unit 32 sends a command of starting the cleaning operation to first
electrostatic charge eliminating unit 33a. When first electrostatic
charge eliminating unit 33a receives the command from control unit
32, the cleaning operation of cleaning the discharge electrode is
started (step SSS3). After predetermined waiting time t.sub.1 has
passed from the start of the cleaning operation by first
electrostatic charge eliminating unit 33a (SSS4), control unit 32
sends a command of starting the cleaning operation to second
electrostatic charge eliminating unit 33b. Second electrostatic
charge eliminating unit 33b receives the command sent from control
unit 32 and starts the cleaning operation of cleaning the discharge
electrode (SSS5). Other electrostatic charge eliminating units 33c,
33d connected to control unit 32 are also cleaned in the same
manner (SSSn). As described above, electrostatic charge eliminating
units 33a to 33d execute the cleaning operation of cleaning the
discharge electrodes in order after waiting time t.sub.1 has
passed.
[0047] After all electrostatic charge eliminating units 33a to 33d
have finished the cleaning operation, when predetermined cycle time
t.sub.2 has passed from the start of first electrostatic charge
eliminating unit 33a (SSSn+1), control unit 32 sends a command of
starting the second time cleaning operation of cleaning the
discharge electrode to first electrostatic charge eliminating unit
33a. First electrostatic charge eliminating unit 33a receives the
command from control unit 32 and starts the second time cleaning
operation of cleaning the discharge electrode (SSSn+2). In the same
manner, the second time cleaning operation is executed for other
electrostatic charge eliminating unit 33b to 33d (SSSn+2 to
SSSn+n). After cycle time t.sub.2 has passed, each electrostatic
charge eliminating unit 33a to 33d repeatedly executes the
operation in order so as to clean the discharge electrodes.
[0048] In this connection, an interval between the cleaning
operation of first electrostatic charge eliminating unit 33a and
that of second electrostatic charge eliminating unit 33b may be
constant or variable when waiting time t.sub.1 is changed at
random. Alternatively, the following constitution may be employed.
As shown in FIG. 17, a plurality of slave units 45, which are
electrostatic charge eliminating units 43b to 43d, are connected to
master unit 44 having control unit 41 and electrostatic charge
eliminating unit 43a in the same housing, so that the system can be
composed. In this case, it is unnecessary to provide a
communicating portion for connecting control unit 41, which is in
the same housing (the master unit 44), to electrostatic charge
eliminating unit 43a. Control unit 41 and electrostatic charge
eliminating unit 43a may be communicated with each other through an
electric power source line. Alternatively, control unit 41 and
electrostatic charge eliminating unit 43a may be communicated with
each other through a communicating line arranged differently from
the electric power source line.
[0049] In this specification, the ionizer and the electrostatic
charge eliminating system are explained above. However, it should
be noted that the present invention is not restricted by the
embodiment disclosed above and variations and improvements of the
present invention may be made. In this specification, explanations
are made into ionizers 3a to 3d and 23a to 23d having the cleaning
portions for cleaning the discharge electrodes. However, instead of
the cleaning portion, a wind direction changing function of
changing a wind direction can be made to be a functional portion,
that is, it should be noted that a form of the functional portion
is not restricted by a specific embodiment. Further, the ionizer
may be provided with a rectifier or a transformer and the electric
power sent from electric power source 2 may be converted and
consumed.
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